FreeBSD/Linux Kernel Cross Reference
sys/dev/uart/uart_dev_lowrisc.c

     /*-
      * SPDX-License-Identifier: BSD-2-Clause
      *
      * Copyright (c) 2018 Ruslan Bukin <br@bsdpad.com>
      * All rights reserved.
      *
      * This software was developed by SRI International and the University of
      * Cambridge Computer Laboratory (Department of Computer Science and
      * Technology) under DARPA contract HR0011-18-C-0016 ("ECATS"), as part of the
     * DARPA SSITH research programme.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_ddb.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/conf.h>
    #include <sys/kdb.h>
    #include <machine/bus.h>
    #include <machine/sbi.h>
    
    #include <dev/uart/uart.h>
    #include <dev/uart/uart_cpu.h>
    #include <dev/uart/uart_cpu_fdt.h>
    #include <dev/uart/uart_bus.h>
    #include <dev/uart/uart_dev_lowrisc.h>
    
    #include "uart_if.h"
    
    #define DEFAULT_BAUD_RATE       115200
    
    /*
     * Low-level UART interface.
     */
    static int lowrisc_uart_probe(struct uart_bas *bas);
    static void lowrisc_uart_init(struct uart_bas *bas, int, int, int, int);
    static void lowrisc_uart_term(struct uart_bas *bas);
    static void lowrisc_uart_putc(struct uart_bas *bas, int);
    static int lowrisc_uart_rxready(struct uart_bas *bas);
    static int lowrisc_uart_getc(struct uart_bas *bas, struct mtx *);
    
    static struct uart_ops uart_lowrisc_uart_ops = {
            .probe = lowrisc_uart_probe,
            .init = lowrisc_uart_init,
            .term = lowrisc_uart_term,
            .putc = lowrisc_uart_putc,
            .rxready = lowrisc_uart_rxready,
            .getc = lowrisc_uart_getc,
    };
    
    static int
    lowrisc_uart_probe(struct uart_bas *bas)
    {
    
            return (0);
    }
    
    static u_int
    lowrisc_uart_getbaud(struct uart_bas *bas)
    {
    
            return (DEFAULT_BAUD_RATE);
    }
    
    static void
    lowrisc_uart_init(struct uart_bas *bas, int baudrate, int databits, 
        int stopbits, int parity)
    {
    
            /* TODO */
    }
    
    static void
    lowrisc_uart_term(struct uart_bas *bas)
   {
   
           /* TODO */
   }
   
   static void
   lowrisc_uart_putc(struct uart_bas *bas, int c)
   {
   
           while (GETREG(bas, UART_DR) & DR_TX_FIFO_FULL)
                   ;
   
           SETREG(bas, UART_DR, c);
   }
   
   static int
   lowrisc_uart_rxready(struct uart_bas *bas)
   {
   
           if (GETREG(bas, UART_DR) & DR_RX_FIFO_EMPTY)
                   return (0);
   
           return (1);
   }
   
   static int
   lowrisc_uart_getc(struct uart_bas *bas, struct mtx *hwmtx)
   {
           uint32_t reg;
   
           uart_lock(hwmtx);
           SETREG(bas, UART_INT_STATUS, INT_STATUS_ACK);
           reg = GETREG(bas, UART_DR);
           uart_unlock(hwmtx);
   
           return (reg & 0xff);
   }
   
   /*
    * High-level UART interface.
    */
   struct lowrisc_uart_softc {
           struct uart_softc base;
   };
   
   static int lowrisc_uart_bus_attach(struct uart_softc *);
   static int lowrisc_uart_bus_detach(struct uart_softc *);
   static int lowrisc_uart_bus_flush(struct uart_softc *, int);
   static int lowrisc_uart_bus_getsig(struct uart_softc *);
   static int lowrisc_uart_bus_ioctl(struct uart_softc *, int, intptr_t);
   static int lowrisc_uart_bus_ipend(struct uart_softc *);
   static int lowrisc_uart_bus_param(struct uart_softc *, int, int, int, int);
   static int lowrisc_uart_bus_probe(struct uart_softc *);
   static int lowrisc_uart_bus_receive(struct uart_softc *);
   static int lowrisc_uart_bus_setsig(struct uart_softc *, int);
   static int lowrisc_uart_bus_transmit(struct uart_softc *);
   static void lowrisc_uart_bus_grab(struct uart_softc *);
   static void lowrisc_uart_bus_ungrab(struct uart_softc *);
   
   static kobj_method_t lowrisc_uart_methods[] = {
           KOBJMETHOD(uart_attach,         lowrisc_uart_bus_attach),
           KOBJMETHOD(uart_detach,         lowrisc_uart_bus_detach),
           KOBJMETHOD(uart_flush,          lowrisc_uart_bus_flush),
           KOBJMETHOD(uart_getsig,         lowrisc_uart_bus_getsig),
           KOBJMETHOD(uart_ioctl,          lowrisc_uart_bus_ioctl),
           KOBJMETHOD(uart_ipend,          lowrisc_uart_bus_ipend),
           KOBJMETHOD(uart_param,          lowrisc_uart_bus_param),
           KOBJMETHOD(uart_probe,          lowrisc_uart_bus_probe),
           KOBJMETHOD(uart_receive,        lowrisc_uart_bus_receive),
           KOBJMETHOD(uart_setsig,         lowrisc_uart_bus_setsig),
           KOBJMETHOD(uart_transmit,       lowrisc_uart_bus_transmit),
           KOBJMETHOD(uart_grab,           lowrisc_uart_bus_grab),
           KOBJMETHOD(uart_ungrab,         lowrisc_uart_bus_ungrab),
           { 0, 0 }
   };
   
   static struct uart_class uart_lowrisc_class = {
           "lowrisc",
           lowrisc_uart_methods,
           sizeof(struct lowrisc_uart_softc),
           .uc_ops = &uart_lowrisc_uart_ops,
           .uc_range = 0x100,
           .uc_rclk = 12500000, /* TODO: get value from clock manager */
           .uc_rshift = 0
   };
   
   static struct ofw_compat_data compat_data[] = {
           {"lowrisc-fake",        (uintptr_t)&uart_lowrisc_class},
           {NULL,                  (uintptr_t)NULL},
   };
   UART_FDT_CLASS_AND_DEVICE(compat_data);
   
   static int
   lowrisc_uart_bus_attach(struct uart_softc *sc)
   {
           struct uart_bas *bas;
           struct uart_devinfo *di;
   
           bas = &sc->sc_bas;
           if (sc->sc_sysdev != NULL) {
                   di = sc->sc_sysdev;
                   lowrisc_uart_init(bas, di->baudrate, di->databits, di->stopbits,
                       di->parity);
           } else
                   lowrisc_uart_init(bas, DEFAULT_BAUD_RATE, 8, 1, 0);
   
           (void)lowrisc_uart_bus_getsig(sc);
   
           /* TODO: clear all pending interrupts. */
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_detach(struct uart_softc *sc)
   {
   
           /* TODO */
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_flush(struct uart_softc *sc, int what)
   {
   
           /* TODO */
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_getsig(struct uart_softc *sc)
   {
   
           /* TODO */
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
   {
           struct uart_bas *bas;
           int error;
   
           bas = &sc->sc_bas;
           error = 0;
           uart_lock(sc->sc_hwmtx);
           switch (request) {
           case UART_IOCTL_BREAK:
                   /* TODO */
                   break;
           case UART_IOCTL_BAUD:
                   *(u_int*)data = lowrisc_uart_getbaud(bas);
                   break;
           default:
                   error = EINVAL;
                   break;
           }
           uart_unlock(sc->sc_hwmtx);
   
           return (error);
   }
   
   static int
   lowrisc_uart_bus_ipend(struct uart_softc *sc)
   {
           struct uart_bas *bas;
           int ipend;
   
           bas = &sc->sc_bas;
   
           ipend = 0;
   
           uart_lock(sc->sc_hwmtx);
           if ((GETREG(bas, UART_DR) & DR_RX_FIFO_EMPTY) == 0)
                   ipend |= SER_INT_RXREADY;
           SETREG(bas, UART_INT_STATUS, INT_STATUS_ACK);
           uart_unlock(sc->sc_hwmtx);
   
           return (ipend);
   }
   
   static int
   lowrisc_uart_bus_param(struct uart_softc *sc, int baudrate, int databits,
       int stopbits, int parity)
   {
   
           uart_lock(sc->sc_hwmtx);
           lowrisc_uart_init(&sc->sc_bas, baudrate, databits, stopbits, parity);
           uart_unlock(sc->sc_hwmtx);
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_probe(struct uart_softc *sc)
   {
           int error;
   
           error = lowrisc_uart_probe(&sc->sc_bas);
           if (error)
                   return (error);
   
           /*
            * On input we can read up to the full fifo size at once.  On output, we
            * want to write only as much as the programmed tx low water level,
            * because that's all we can be certain we have room for in the fifo
            * when we get a tx-ready interrupt.
            */
           sc->sc_rxfifosz = 2048;
           sc->sc_txfifosz = 2048;
   
           device_set_desc(sc->sc_dev, "lowRISC UART");
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_receive(struct uart_softc *sc)
   {
           struct uart_bas *bas;
           uint32_t reg;
   
           bas = &sc->sc_bas;
   
           uart_lock(sc->sc_hwmtx);
   
           do {
                   if (uart_rx_full(sc)) {
                           /* No space left in the input buffer */
                           sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
                           break;
                   }
                   reg = GETREG(bas, UART_DR);
                   SETREG(bas, UART_INT_STATUS, INT_STATUS_ACK);
                   uart_rx_put(sc, reg & 0xff);
           } while ((reg & DR_RX_FIFO_EMPTY) == 0);
   
           uart_unlock(sc->sc_hwmtx);
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_setsig(struct uart_softc *sc, int sig)
   {
   
           return (0);
   }
   
   static int
   lowrisc_uart_bus_transmit(struct uart_softc *sc)
   {
           struct uart_bas *bas;
           int i;
   
           bas = &sc->sc_bas;
   
           uart_lock(sc->sc_hwmtx);
           for (i = 0; i < sc->sc_txdatasz; i++) {
                   while (GETREG(bas, UART_DR) & DR_TX_FIFO_FULL)
                           ;
                   SETREG(bas, UART_DR, sc->sc_txbuf[i] & 0xff);
           }
           uart_unlock(sc->sc_hwmtx);
   
           return (0);
   }
   
   static void
   lowrisc_uart_bus_grab(struct uart_softc *sc)
   {
           struct uart_bas *bas;
   
           bas = &sc->sc_bas;
   
           uart_lock(sc->sc_hwmtx);
           /* TODO */
           uart_unlock(sc->sc_hwmtx);
   }
   
   static void
   lowrisc_uart_bus_ungrab(struct uart_softc *sc)
   {
           struct uart_bas *bas;
   
           bas = &sc->sc_bas;
   
           uart_lock(sc->sc_hwmtx);
           /* TODO */
           uart_unlock(sc->sc_hwmtx);
   }

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